But can it improve cognitive function, an indicator of worker productivity? Joseph Allen, an assistant professor at Harvard University’s T. H. Chan School of Public Health, decided to find out.

Allen and his team arranged for 24 office workers—managers, architects, and designers—to work for two weeks in a highly-controlled office environment. Meanwhile, without telling the workers, the researchers introduced varying levels of fresh outdoor air, carbon dioxide, and volatile gases typically emitted by office furniture and cleaners.

“At the end of each day, we tested the workers’ decision-making performance using a standardized cognitive function test that researchers have used for decades,” explained Allen.

The result? The workers made significantly better decisions when they breathed fresh air. The biggest improvements came when they used information to “plan, stay prepared, and strategize during crises,” reports Allen. “These are exactly the skills needed to be productive in the knowledge economy.”

Allen’s team then went on to repeat their findings in a variety of buildings across the United States.

“In most buildings, managers can take action immediately, by improving air quality through higher ventilation rates,” says Allen. He estimates that doubling the office ventilation could lift employee productivity up to US$6,500 per person per year, as well as reduce sick building syndrome and absenteeism.”

“We’ve all struggled to concentrate in a conference room that is stuffy and warm,” says Allen. “When a window or door is opened and fresh air comes in, it breathes life into the room. Businesses would benefit from recognizing this and taking action to optimize their air quality for employees’ health and productivity.”